The African Breast Cancer - Disparities in Outcomes (ABC-DO) study is a within-Africa, multi-country study of factors that affect breast cancer outcomes for patients at public hospitals across different sub-Saharan African settings. In four public hospital settings, ABC-DO will examine the full journey of breast cancer patients, from pre-diagnosis right through the post-diagnosis treatment period for up to 3 years. ABC-DO will study both immediate biological factors (prognostic factors, tumour biology, and treatment received) and distal factors that represent barriers to early presentation and diagnosis, and receipt of timely and appropriate treatment.